Laryngoscopes, also known as glottiscopes, are routinely used to facilitate endotracheal intubation of patients, e.g., to provide a temporary air passage for administration of anesthetic substance or to overcome an obstruction of the air passage to a patient's lungs. Glottiscopes, in various forms, provide the surgeon with access to examine and surgically manipulate the vocal folds and operate to distract the soft tissues of the oral cavity, pharynx and supraglottic larynx. This is a procedure known as direct laryngoscopy.
A typical glottiscope has an elongate element, which may be of variable geometry, that is introduced through the patient's mouth into the larynx. An attached handle enables the surgeon to manipulate not only the element introduced into the patient's larynx but, as appropriate, to position the distal end of the inserted element to perform inspection and/or surgical operations. The glottiscope typically includes a lumen, through which an endotracheal tube or alternatively, one or more surgical tools can be simultaneously inserted. Otolaryngologists typically use a tubular glottiscope, which is inserted into the patient's larynx to the glottis, i.e., the true vocal cords or folds, both for viewing and for endoscopic surgical operations.
The surgeon must have a clear view of the affected tissue and must be able to perform precise surgery, sometimes with more than one tool utilized simultaneously. Because of the limited dimensions of the human oral cavity, pharynx and larynx, it is extremely important to enable the surgeon to have the widest access and maximum freedom for manipulating necessary instrumentation, and to reduce the time during which physical invasion of the patient's larynx must occur.
Particularly for patients who need to improve or maintain their voices, specialized surgery known as phonomicrosurgery is performed with the use of a surgical microscope. Such phonomicrosurgery is optimized by obtaining the widest glottal surgical field to expose vocal-fold anomalies such as polyps, nodules, cysts, granulomas, papilloma, epithelial dysplasia, and cancerous growths.
The human vocal folds (glottis) comprise an approximately isosceles-triangle-shaped valve that is fixed anteriorly and opens and closes posteriorly to respectively allow for respiration and phonation. Lesions of the vocal folds may occur in patients of all ages and of both genders. A clear human voice is predicated on aerodynamically-driven, symmetrically-entrained oscillation of the vocal folds. When the vocal folds are closed during phonation, the expired air stream from the trachea is opposed by the closed glottal valve. Under sustained aerodynamic pressure, the vocal folds will vibrate to generate phonation. If there is a lesion on the vocal folds, this vibration becomes disordered, and hoarseness develops. Most benign lesions of the vocal folds, except lesions caused by viral infection, tend to develop in vocal over-users.
The design goal of any glottiscope is to provide an internal portion, or lumen, that provides the widest internal viewing and working area. This is achieved by minimizing the differential between the inner and outer diameter of the tube and by optimally designing the contours of the tube, as discussed in U.S. Pat. No. 5,893,830 to Zeitels. This allows for the placement and advancement of the largest glottiscope possible through the aforementioned soft tissues. A narrower outer diameter of the tube also allows for easier placement and insertion of the glottiscope.
The placement of any glottiscope requires illumination to facilitate the maneuvering and to avoid unnecessary tissue trauma. In 1895, the first illumination was provided by a headlight, and in the 20th century, light carriers were attached to the laryngoscopes. In present glottiscopes, however, small bulbs, fiber-optics, or polymers that transmit light are typically used to provide illumination. In these present models, problems result from the light carrier widening the outer diameter of glottiscope. A problem with placing the light carrier laterally on the glottiscope is that the light carrier widens the outer diameter of the glottiscope and impairs placement of the glottiscope if the individual has a small mandible.
Another problem can result if the light carrier is situated in part or completely within the lumen of the glottiscope. Any light carrier that commences outside the laryngoscope tube must eventually enter the lumen to provide internal illumination. This leads to partial obstruction of the intralumenal visual/surgical field. Furthermore, the position of the light carrier can inhibit the range of motion of hand instruments and/or preclude the use of a laser in certain locations of the visual/surgical field. The obstruction of the visual/surgical field induced by the light carrier varies by degree but is present in all current models of tubular glottiscopes.
In certain glottiscope models, in which the light carrier remains entirely within the lumen of the laryngoscope tube, the placement of the light carrier leads to even worse obstruction than previously described. The advantage, however, of an internal light carrier is that the outer diameter of the tube is narrower, which facilitates the advancement of the glottiscope past the mandible and the associated soft tissues. The need for a suction aspiration cannula, in addition to the light-carrier, exacerbates even further both problems described above. Accordingly, a need exists for an improved glottiscope design that provides for illumination and suction in which the lumen, and therefore the visual/surgical field, is not obstructed and in which the advancement of the glottiscope is not impaired by an enlarged diameter of the glottiscope.